EDK: Convert remaining scoped_ptr -> std::unique_ptr in //mojo/edk/system.

mojo/edk/system/endpoint_relayer.cc

Index: mojo/edk/system/endpoint_relayer.cc
diff --git a/mojo/edk/system/endpoint_relayer.cc b/mojo/edk/system/endpoint_relayer.cc
index 901765151dccf462f3ceed182888ce0ead5fe395..5634db0cab2c9fd90c96d19afa634bfe0a2a3a99 100644
--- a/mojo/edk/system/endpoint_relayer.cc
+++ b/mojo/edk/system/endpoint_relayer.cc
@@ -55,8 +55,10 @@ bool EndpointRelayer::OnReadMessage(unsigned port, MessageInTransit* message) {
   }
 
   // Otherwise, consume it even if the peer port is closed.
-  if (endpoints_[peer_port])
-    endpoints_[peer_port]->EnqueueMessage(make_scoped_ptr(message));
+  if (endpoints_[peer_port]) {
+    endpoints_[peer_port]->EnqueueMessage(
+        std::unique_ptr<MessageInTransit>(message));
+  }
   return true;
 }